The objective of this project is to contribute to a more detailed understanding of the electronic and vibrational structure of the class of porphyrin molecules. Spectroscopic experiments are in progress in which free base and metal complexes of porphin are incorporated as guest molecules into crystalline aromatic hosts. High resolution low temperature optical spectroscopy, selective excitation spectroscopy, and electron spin resonance techniques are used in the study of both single crystal and polycrystalline specimens. A dye laser is used as an excitation source for selective excitation studies. BIBLIOGRAPHIC REFERENCE: "Optical Spectra of Ni Porphin, Pd Porphin, and Free Base Porphin in Single Crystal Triphenylene", Joseph Bohandy and Boris F. Kim, Spectrochimica Acta (1976). (In press.)